The present invention relates to endoscopes and to covers or sleeves for endoscopes.
Flexible endoscopic equipment has been used in medicine since the late 1960's; however, the basic design of the equipment has not changed significantly since the early 70's. Its main use is in the diagnosis and treatment of gastrointestinal disorders because internal organs can be directly visualised, abnormalities targeted and specimens removed for microscopic analysis. Endoscopy has also become important in treating patients because surgical instruments can be introduced through the endoscope. Small tumors can be removed, laser therapy performed, injections given, narrowed areas can be stretched and foreign bodies removed. Early endoscopes included fibre optics for viewing purposes, but more modern endoscopes operate on video imaging principles using an electronic chip with the image being displayed on a television screen.
There are four main types of endoscope used in gastroenterology: an upper digestive endoscope passed through the mouth for examination of the gullet, stomach and the duodenum; a duodenoscope for pancreatico-bilary work; a colonoscope for inspection of the large intestine (colonoscopy); and an enteroscope for inspection of the small intestine (enteroscopy).
In order to perform colonoscopy patients first undergo a stringent laxative regimen in order to clear the large intestine of fecal matter. They are given a light sedative and an analgesic and the flexible endoscopic instrument is introduced through the anus and passed up through the large intestine. The limit of the examination is usually the caecum which is the upper most part of the large bowel but skilled operators can introduce the instrument into the lower part of the small intestine.
The performance of colonoscopy is technically difficult and requires a long period of learning. Even after training, some operators are more skillful than others and are able to perform the procedure more quickly, safely and effectively than others. The reason why the procedure can be difficult is that the colon is variable in its shape and configuration. It comprises a series of loops which are tethered within the abdomen in certain places by the blood vessels and connective tissue which supply the organ whereas in other parts, the colon is relatively free to move around within the abdominal cavity. When a flexible, but fairly stiff instrument is inserted into the bowel there is a tendency for looping to occur. When this happens the skilled operator is able to reduce the size of the loop and concertina the bowel over the instrument. By twisting, pushing, pulling and angling of the tip of the instrument progress is made around the bowel until the caecum is reached. Less skilled endoscopists find this difficult and often large loops are formed within the abdomen. When this occurs not only is further progress difficult, but it is painful for the patient and there are potential risks that the mesentry may be pulled excessively. The length of time to reach the caecum varies from 10 minutes to over one hour and, on occasions it is not possible to reach the caecum at all.
Colonoscopy is the most effective technique available for examining the large intestine. Not only has it been advocated as a diagnostic test for patients with colonic symptoms and diseases it is also used for cancer screening. (Colonic cancer in the United Kingdom is the second commonest lethal cancer.) The particular relevance of colonoscopy is that these cancers usually begin as small polyps which can be easily removed by the colonoscope before they become malignant and it would be possible to reduce the risk of cancer very substantially if colonoscopy was easy and simple. However, its popularity as a screening technique is limited by expense of the procedure and the unpleasantness to the patient. If it were possible to reach the caecum regularly within a short period of time and without discomfort the technique would be more widely applicable.
It has been estimated recently that in the United Kingdom alone as many as 250,000 colonoscopic examinations are performed per annum. If it was more acceptable and cheaper the number would be considerably in excess of this. The main expense relates to staffing and overheads rather than capital equipment, thus if more patients could be examined per unit time the costs would fall considerably.
Enteroscopy is not a commonly used procedure, one main reason for which is its difficulty. The small intestine is the longest part of the gastrointestinal tract and it can be reached only by passing the endoscope first through the gullet, stomach and duodenum; only then is the small intestine entered. The small intestine itself is convoluted with many twists and turns and attempts to advance the enteroscope through the small intestine is difficult, painful and enables only the upper part of the small intestine to be examined. The reason for this is that when using a "push" enteroscope the bends that occur in the enteroscope prevent it from advancing with the result that it tends to coil up and looping occurs. Another way of doing enteroscopy is to use a "pull" enteroscope which is much thinner and is passed through the nose and then allowed to travel (as food does) under its own momentum through the small intestine. It can be withdrawn and the small intestine can be viewed as it comes out. Unfortunately it tends to slip rapidly around, twisting and turning and the whole intestine still cannot be easily seen. Furthermore because it is so thin it is not possible to carry out treatment procedures through it.